Programmable power supply

ABSTRACT

A power supply system includes a power source and a control circuit. The power source provides DC power. A control circuit, which is remote to the power source, receives the DC power and provides a first DC power signal to an electronic device. The control circuit includes an active component to provide at least one of a voltage control output or a current control output to the power source to regulate the DC power. A power supply system includes a power source and a control circuit. The control circuit is remote to the power source, receives the DC power, and provides the DC power to an electronic device. The control circuit includes a microprocessor to provide at least one of a voltage control output and a current control output to the power source to regulate the DC power.

RELATED APPLICATIONS

This application is a continuation application of utility applicationSer. No. 10/927,566, filed Aug. 26, 2004, now U.S. Pat. No. 6,922,347,which is a divisional application of utility application Ser. No.10/313,793, filed Dec. 5, 2002, now U.S. Pat. No. 6,809,943, which is acontinuation application of utility application Ser. No. 10/140,513,filed May 7, 2002, now U.S. Pat. No. 6,693,413, which is a continuationapplication of utility application Ser. No. 09/694,972, now abandoned,which is a continuation-in-part application of utility application Ser.No. 09/310,461, filed May 12, 1999, now U.S. Pat. No. 6,172,884, whichis a continuation-in-part application of utility application Ser. No.09/213,018, filed Dec. 16, 1998, now U.S. Pat. No. 5,949,213, which is acontinuation-in-part application of utility application Ser. No.09/148,811, filed Sep. 4, 1998, now U.S. Pat. No. 6,091,611, which is acontinuation application of utility application Ser. No. 08/994,905,filed Dec. 19, 1997, now U.S. Pat. No. 5,636,110, which is acontinuation-in-part of utility application Ser. No. 08/767,307, filedDec. 16, 1996, now abandoned, which is a continuation-in-partapplication of utility application Ser. No. 08/567,369, filed Dec. 4,1995, now U.S. Pat. No. 5,636,110, and claims priority of provisionalapplication Ser. No. 60/002,488 filed Aug. 17, 1995, and is also acontinuation-in-part application of utility application Ser. No.08/233,121 filed Apr. 26, 1994, now U.S. Pat. No. 5,479,331.

NOTICE OF COPYRIGHTS

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patentdisclosure, as it appears in the United States Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to power supplies and in particular relates topower supplies for use with a variety of different devices.

2. Background of the Invention

Prior art power supplies include a variety of techniques, particularlythose used for powering microelectronics such as the class of Computerscommonly known as “notebook” computers such as the Powerbook Seriesavailable from Apple Computer of Cupertino Calif. and the ThinkpadSeries available from International Business Machines (IBM) of Armonk,N.Y. More recently, even smaller personal computers referred to as“sub-notebooks” have also been developed by various companies such asHewlett-Packard's Omnibook. The goal of these notebooks andsub-notebooks designs is to reduce the size and weight of the product.Currently, notebooks typically weigh about six pounds and sub-notebooksweigh slightly less than four pounds.

Many of these notebook and sub-notebook computers have a battery thatmust be recharged. Also, typically the computers are designed to beoperated from external power sources such as line current and theelectrical power system of automobiles.

To power these computers, the manufacturer typically provides anexternal power source. The external power source may be a switchingpower supply that may weigh close to a pound and may be about eightinches long, four inches wide and about four inches high. Smaller powersupplies do exist but frequently they lack sufficient power to chargenew batteries such as nickel hydride batteries.

Such external power supplies therefore contribute substantial additionalweight that the user of the computer must carry with him or her topermit battery charging and/or operation from an electrical socket.Further, the external power supply is bulky and may not be readilycarried in typical cases for such notebook and sub-notebook computers.In addition, conventional power supplies often have difficulty providingthe necessary power curve to recharge batteries that have beenthoroughly discharged. Also, a power supply is needed for eachperipheral device, such as a printer, drive or the like. Thus, a userneeds multiple power supplies.

While it has long been known to be desirable to reduce the size andweight of the power supply, this has not been readily accomplished. Manyof the components such as the transformer core are bulky and havesignificant weight. Further, such power supplies may need to be able toprovide DC power of up to seventy-five watts, thereby generatingsubstantial heat. Due to the inherent inefficiencies of power supplies,this results in substantial heat being generated within the powersupply. Reduction of the volume, weight and heat are all criticalconsiderations for a power supply in this type of application and cannotbe readily accomplished. In particular, it is believed to be desirableto have a package as thin as possible and designed to fit within astandard pocket on a shirt or a standard calculator pocket on a briefcase. In addition, conventional power supplies are device specific andeach device requires its own power supply. Therefore, users needmultiple power supplies, which consumes space and increases unnecessaryweight.

Cellular telephones are also extensive users of batteries. Typically,cellular telephone battery chargers have been bulky and are not readilytransportable. Moreover, cellular telephone battery chargers often takeseveral hours, or more, to charge a cellular telephone battery.

SUMMARY OF THE INVENTION

It is an object of an embodiment of the present invention to provide animproved small form factor power supply that is resistant to liquidsand/or is programmable to supply power for a variety of differentdevices, which obviates for practical purposes, the above mentionedlimitations.

These and other objects are accomplished through novel embodiments of apower supply having a transformer. The primary portion includes aprimary rectifier circuit, a controller, first and secondary primarydrive circuits each coupled magnetically by a coil to the core and aprimary feedback circuit magnetically coupled by a separate core. Thesecondary portion includes a secondary output circuit magneticallycoupled by a coil to the core that provides the regulated DC output anda secondary feedback back circuit magnetically coupled to the secondcore to provide a signal to the primary feedback circuit. In alternativeembodiments, different transformer topologies may be used.

The controller provides a separate square wave signal to each of the twoprimary circuits and the phase of the square wave signals may be alteredrelative to each other as determined by the controller. The secondarycircuit is positioned on the core relative to the two primary circuitsso that the secondary circuit coil is positioned at a summing point onthe core of the first and second primary circuit coils. The DC voltageand current levels produced at the output of the secondary circuit aremonitored by the secondary feedback circuit to provide, through asecondary feedback coil and a primary feedback coil, a signal to thecontroller. The controller alters the phase between the signals drivingthe two coils to produce the desired output DC voltage and current atthe secondary coils. This results in providing a regulated DC powersupply with high efficiency.

By mounting all of the components on a printed circuit board usingplanar or low profile cores and surface mounted integrated circuits, asmall form factor power supply can be attained. Given the highefficiency of the conversion and regulation, the system minimizesdissipation of heat permitting the entire power supply to be mountedwithin a high impact plastic container dimensioned, for example, as aright parallelepiped of approximately 2.85×5.0×0.436 inches, therebyproviding a power supply that can readily be carried in a shirt pocket.It should be understood that changes in the overall dimensions may bemade without departing from the spirit and scope of the presentinvention. Making a relatively thin package having relatively large topand bottom surface areas relative to the thickness of the packageprovides adequate heat dissipation.

Particular embodiments of the present invention utilize an improvedtransformer core that, by moving the relative position of thetransformer legs, maximizes a ratio of the cross-sectional area of thetransformer legs to the windings, thereby requiring less windings forthe same magnetic coupling. Fewer windings means less area of a layer ofa circuit board may be used so that the number of layers on the circuitboard may be minimized. The improved transformer core also provides thismaximized ratio while maintaining the ratio of the secondary and primarywindings at a constant value. In alternative embodiments, differenttransformer topologies may be used.

It is an object of an additional embodiment of the present invention toalleviate the need for having a separate power supply for providingpower for using each portable electronic device having distinct powerrequirements.

It is another object of the additional embodiment of the presentinvention to provide a power supply which is programmable to transmit anappropriate input power to any one of several electrically powereddevices.

Briefly, the additional embodiment of the present invention is directedto a power supply which is programmable for providing between about zeroand seventy five watts of power DC to a portable electronic applianceadapted for receiving DC power at one of an operational current and anoperational voltage. The power supply comprises an input circuit forreceiving input power from a power source, an output circuit adapted forcoupling to the electronic appliance at an output connection fortransmitting power to the electronic appliance and a power conversioncircuit for providing output power at the operational current or theoperational voltage in response to a detection of one of a programmingsignal received at the output connection.

The power supply may be configured to be programmable to support avariety of different devices and/or more than one device at a time. Thismay be accomplished with an on-board processor or by using externalcables to provide the programming signal. Thus, the need for havingmultiple power supply devices (each adapted for meeting the powerrequirements of a distinct portable device) for providing power todifferent portable devices.

Other features and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings which illustrate, by way of example, variousfeatures of embodiments of the invention.

BRIEF DESCRIPTION OF THE FIGURES

A detailed description of embodiments of the invention will be made withreference to the accompanying drawings, wherein like numerals designatecorresponding parts in the several figures.

FIG. 1 is a block diagram of a first embodiment of the disclosedinvention.

FIG. 2 is a sectional view of the E core for use in the embodiments ofFIG. 1.

FIG. 3 is a detailed circuit schematic of the embodiment of FIG. 1.

FIG. 4 is a top planar view of a printed circuit board containing thecircuit of FIG. 3.

FIG. 5A is a top planar view of a case or housing for an additionalembodiment of the for an invention where the case houses the othercomponents.

FIG. 5B is a partial cross-section of the louvers and openings of thecase top as shown in FIG. 5A.

FIG. 5C is a partial cross-section of another embodiment of the louversformed from raised ridges and depressions on the case top.

FIG. 6 is a top planar view of one of two heat sinks for the additionalembodiment of the invention that sandwich a printed circuit boardcontaining the circuitry for the additional embodiment.

FIGS. 7A and 7B are a schematic diagram of the additional embodiment ofthe invention.

FIG. 7C is a schematic diagram of a switch mechanism that may be used toselect a resistor from among a plurality of resistors in order for thepower supply to produce a desired output voltage or output current.

FIG. 8 is a timing diagram for the circuit shown in FIGS. 7A and 7B.

FIG. 9 is a block diagram of the U1 integrated circuit shown in FIG. 7.

FIGS. 10A and B are timing diagrams for the block diagram shown in FIG.9.

FIG. 11 is a power versus output current curve and an output voltageversus current curve of a power supply in accordance with an embodimentof the present invention.

FIGS. 12A–12C are a top plan view and two side plan views of atransformer core in accordance with another embodiment of the presentinvention.

FIGS. 13A–13C are a top plan view and two side plan views of atransformer cap for use with the transformer core shown in FIGS.12A–12C.

FIG. 14 is a top plan view of a printed circuit board layer, withoutwinding patterns, to be coupled with the transformer core shown in FIGS.12A–12C.

FIG. 15 is a top plan view of another printed circuit board layershowing a secondary winding pattern to be coupled with to thetransformer core shown in FIGS. 12A–12C.

FIG. 16 is a top plan view of another printed circuit board layershowing a primary winding pattern to be coupled with the transformercore shown in FIGS. 12A–12C.

FIGS. 17A–17C are a top plan view and two side plan views of atransformer core in accordance with an alternative embodiment of thepresent invention.

FIGS. 18A–18C are a top plan view and two side plan views of atransformer cap for use with the transformer core shown in FIGS.17A–17C.

FIG. 19 is a top plan view of a printed circuit board layer with asecondary winding pattern to be coupled with the transformer core shownin FIGS. 17A–17C.

FIG. 20 is a top plan view of another printed circuit board layershowing primary winding patterns to be coupled with the transformer coreshown in FIGS. 17A–17C.

FIG. 21 is a top plan view of another printed circuit board layershowing additional primary winding patterns to be coupled with thetransformer core shown in FIGS. 17A–17C.

FIG. 22 is a top plan view of another printed circuit board layershowing a another secondary winding pattern to be coupled with thetransformer core shown in FIGS. 17A–17C.

FIG. 23 is a schematic of a control circuit in accordance with anembodiment of the present invention.

FIG. 24 is a schematic of a programming circuit in accordance with anembodiment of the present invention that is used to digitally programthe power supply to produce between 0 and 16 volts.

FIG. 25 is a schematic of another programming circuit in accordance withan embodiment of the present invention that is used to digitally programthe power supply to produce between 16 and 18 volts.

FIG. 26 is an end view of a connector that mates with the small formfactor power supply and is useable to program the small form factorpower supply.

FIGS. 27( a)–27(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 28( a)–28(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 29( a)–29(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 30( a)–30(b) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 31( a)–31(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 32( a)–32(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 33( a)–33(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 34( a)–34(c) show a cable with connections in accordance with anembodiment of the present invention to program the small form factorpower supply for supplying power to different devices;

FIGS. 35( a)–40(c) show various connector adapters four use with thecable shown above in FIGS. 34( a)–34(c).

FIGS. 41( a) and 41(b) illustrate a block diagram and a schematic of aninterface for providing power to more than one device at a time.

FIG. 42 shows a top and rear perspective view of a small form factorpower supply for use with portable telephone equipment.

FIG. 43 shows a top and front perspective view of the small form factorpower supply shown in FIG. 42.

FIG. 44 shows a bottom and front perspective view of the small formfactor power supply shown in FIG. 42.

FIG. 45 shows a side perspective view of the small form factor powersupply shown in FIGS. 42–44 connected to a cellular telephone batteryand telephone.

FIG. 46 shows a top front perspective view of the small form factorpower supply shown in FIGS. 42–44 connected to a cellular telephonebattery and telephone.

FIG. 47 shows a top and front perspective view of a small form factorpower supply adapter connector for use with portable telephoneequipment.

FIG. 48 shows a top perspective view of the adapter connector shown inFIG. 47.

FIG. 49 shows a bottom perspective view of the adapter connector shownin FIG. 47

FIG. 50 shows a right side view of the adapter connector shown in FIG.47.

FIG. 51 shows a schematic diagram of an alternative embodiment of apower supply which receives input power from a DC source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the drawings for purposes of illustration, embodiments ofthe present invention are directed to an improved small form factorpower supply. In preferred embodiments of the present invention, thesmall form factor power supply is packaged in a small volume andproduces over 75 watts of power with temperatures below 140° F.Preferred embodiments are used to power portable computers. However, itwill be recognized that further embodiments of the invention may be usedwith other electronic devices, such as computer peripherals, audio andvideo electronics, portable telephone equipment and the like.

Other embodiments of the present invention are more generally directedto a power supply which is capable of providing power to any selectedone of a number of electronic devices in response to a programmingsignal. Each of the electronic devices is adapted for receiving inputpower at either a set operational voltage or a set operational current.The programming signal preferably controls the power supply to maintainthe output power at one of an operational current or an operationalvoltage associated with the selected electronic device.

FIG. 1 shows a block diagram of the power supply according to anembodiment of the present invention. All components on the left side ofa magnetic core 20 are part of the primary portion 100 and all portionson the right hand side are part of the secondary portion 200 of thepower supply.

The primary portion 100 includes a primary rectifier and input circuit110, a first primary and drive circuit 120, a second primary and drivecircuit 130, a primary feedback circuit 140 and a controller 150. Thesecondary portion 200 includes a secondary output circuit 210 and asecondary feedback circuit 240.

The function of the primary rectifier and input circuit 110 is to couplethe embodiment 10 to the line voltage (for example 110 volt, 60 Hz), torectify that voltage and provide DC power for the remainder of theprimary portion 100 and a ground path for the primary circuits 120 and130. The controller 150, which may be a Unitrode 3875 provides twosquare wave driver signals 152 and 154 having alterable phases to thefirst and the second primary circuits 120 and 130. The first and secondprimary circuits are resonant circuits that are resonant at about thefrequency of the driver signals and include coils that are coupled tothe core 20, which may be a planar or low profile “E” type core, whichmay be any low loss material, as is shown in a sectional view in FIG. 2.Hence, the driver signals are magnetically coupled to the core 20 byfirst and second primary coils contained within the circuits 120, 130.

The coil 212 in the secondary circuit 210 is preferably positionedrelative to the coils of the two primary cores so that the coil in thesecondary circuit is at a summing point of the magnetic flux from theprimary circuit coils. If a planar or low profile “E” type core as shownin FIG. 2 is used, the coil 212 for the secondary circuit 210 ispositioned about the central leg 22. The coil for the feedback circuits140 is positioned on one of the outer legs 24, 26. As a result, themagnetic flux from the two primary coils of the primary circuits 120,130 are summed at the position where the secondary coil 212 for thesecondary circuit 210 is positioned. (This positioning of the coils isshown in FIG. 1 by using the double line to indicate the central leg 22and a single line to represent the outer legs 24, 26).

The amplitude of the DC voltage and current produced by the secondarycircuit 210 are monitored by the secondary feedback circuit 230. Theprimary feedback circuit 140 and the secondary feedback circuit 230 aremagnetically coupled by coils positioned on another core 23 to provide afeedback signal to the controller 150. In response to the feedbacksignal, the controller alters the relative phase between the two driversignals 152 and 154 to obtain the desired magnitude of the voltage andcurrent. Since the secondary coil 212 is located at a summing point onthe core of the flux from the two primary coils, as the phase betweenthe driving signals 152 and 154 to the two primary coils alters, themagnitude of the current and voltage induced in the secondary coil willvary. This will permit control of the secondary circuit 210 outputvoltage and current, thereby providing a readily controlled outputvoltage.

FIG. 3 shows a more detailed schematic of an embodiment of theinvention. A standard AC plug may be coupled to input nodes 111, 112 toa first filter coil L1 that is coupled to a full wave rectifier bridge113, which may be a MDA106G. Filtering capacitors C1, C2, C7, C8 arealso coupled to the bridge 113 and one side of the bridge is coupled toAC ground.

The other side of the bridge is coupled to the primary coils 122 and 132of the first and second primary circuits 120, 130 respectively. Theother terminal of the primary coils 122, 132 are coupled to theremainder of the primary circuits 120 and 130. Each of these primarycircuits 120, 130 also comprise a drive field effect 124, 134, which maybe a MTP6N60 and a capacitor 126, 136. The coils 122, 132, transistors124, 134 and capacitors 126, 136 are selected so that the resonantfrequency of the circuits 120, 130 is at about the frequency of thedrive signals 152, 154 to maximize the efficiency of the power supply.In this embodiment, the drive signal frequency is about one megahertz,though other frequencies may be used.

The drive signals 152 and 154 are supplied by a controller 150 such as aUnitrode UC3875QP or other similar product. The controller 150 receivesthe biasing power at pins 28 and 1 from the primary power supply circuit160.

Each of the coils 122 and 132 induce a varying magnetic field in theouter legs of the core 20. The secondary coil 212, which has a centertap 213, is coupled to a half wave rectifier bridge 214, which maycomprise an MBRD66OCT, and then is coupled to a filtering circuit 216comprised of a capacitor 218, an inductor 220, and capacitors 222 and224 to provide a DC regulated output 226.

The regulation is provided by feeding back to the controller 150 asignal modulated by a current sensing amplifier circuit 232 and avoltage sensing circuit 240 comprising the feedback circuit 230. Toprovide the carrier for modulation, a further secondary carrier coil 242is coupled to one of the outer legs of the core 20. One of the legs ofthis transformer coil 242 is coupled to an isolation feedbacktransformer T2.

The current sensing circuit takes the output of the center tap of thesecondary coil 212 and provides a voltage drop across resistor R9 thatis provided to current sensing amplifier circuit 232. The output of thecurrent sensing amplifier circuit 232 is added to a voltage droppedacross R13 and is provided to an amplifier 244 in the voltage sensingcircuit 240. The other input in the voltage sensing circuit is areference voltage developed by the Zener reference diode 246 and alsoprovided as a biasing level to the current sensing amplifier circuit232. The output of the amplifier 244 is provided to the base of bipolartransistor Q3, which may be a MMBT2907T, configured in a common baseconfiguration, to amplitude modulate the current through the secondaryside coil 246.

The primary side coil 156 of feedback transformer T2 is magneticallycoupled to the secondary side coil of 246 and generates an amplitudemodulated signal that is envelope detected and integrated to provide afeedback voltage at input 22 of the controller 150.

As a result, as the amplitude of the envelope of the modulated signalincreases, the voltage at input 22 of the controller 150 increases. Whenthe controller 150 determines that the voltage has exceeded apredetermined limit, indicating that either the current or voltage atthe output has increased beyond the predetermined maximum, the relativephase difference of driver signals 152 and 154 is increased. If theamplitude at input 22 decreases below a predetermined thresholdindicating that the voltage or the current is below the desired levels,the relative phase of signals 152 and 154 is decreased towards zero toincrease the voltage or current. Due to the summing effect of themagnetic flux at secondary coil 212, a highly efficient control orregulation of the power supply circuit is obtained.

Because of the high efficiency that is attained with this circuit, heatdissipation is much less and it is possible to reduce the size of powersupply to a much smaller form factor. In particular, each of theelectrical components in FIG. 2, other than the transformer, may bemounted using surface mount devices on a printed circuit board. Further,each of the inductors and transformer cores are low profile or planarcores mounted through cutouts formed in the printed circuit board. Thecoils of the inductors and transformers are provided by wiring traces onthe circuit board that wrap around the portion of the appropriate corepenetrating the circuit board. As a result, an extremely compact formfactor may be obtained. FIG. 4 shows a top planar view of such a printedcircuit board with each inductor L1, L2 and transformer cores T1 and T2identified.

Notwithstanding the smaller size of the form factor, heat dissipation isnot a serious problem due to the increased efficiency of the powersupply according to the disclosed embodiments. Therefore, with all thecomponents assembled on a printed circuit board as described above, theassembled printed circuit board may be housed within a housing formedfrom an injection molded plastic dimensioned 2.75×4.5×0.436 incheswithout undue heating of the housing, although other dimensions may beused with a key to maintaining a thin profile of the power supply beingthe ratio of the surface area of the top and bottom surfaces to theoverall thickness of the housing. With proper heat sinks, for example,even smaller dimensions may be attained. For example, with such ahousing, surface temperatures on the housing should not exceed onehundred twenty degrees Fahrenheit. A normal electrical plug such as aphased, three-prong plug, is coupled by an input cable (not shown)through a hole formed in the housing and an output cable (not shown)having a connector (not shown) coupled to the printed circuit board andto an output connector. Alternatively, the three-prong plug (not shown)may be formed within the housing with the prongs projecting from thehousing to avoid the opening for a cable. Also, the plug may be of apivotable type (not shown) mounted on the surface of the housing androtate between a recessed position in a cutout formed within the housingand an in use position projecting at ninety degrees from the surface ofthe housing.

Although the disclosed embodiment shows only one regulated DC voltagebeing supplied (for example +5 or +16 volts DC), it would readily beunderstood by those of ordinary skill in the field that other regulatedor unregulated voltages may also be supplied with minor modifications tothe disclosed embodiment. For unregulated voltages, additional secondarycoils (not shown) with the appropriate number of windings to provide thevoltage may be magnetically coupled to any of the legs of thetransformer core 120. The appropriate circuitry must then be providedfor rectifying and filtering the output of this additional secondarycoil. Similarly, an additional regulated voltage may be supplied byproviding a feedback control circuit such as the type described abovethat provides the appropriate feedback.

FIG. 5A shows a top planar view of a case 300 for an additionalembodiment of the invention substantially having the shape of a rightparallelepiped. The case may have dimensions of 5 inches long by 2.85inches wide and the thickness (not shown) is 0.436 inches. Both the topportion of the case 300 and the bottom portion (not shown) define anumber of louvers 304 defining multiple openings 302. The configurationof the openings 302 on both the top and bottom (not shown) portions ofthe cover are relatively unimportant. These openings must, howeverprovide sufficient air circulation so that even when operating atmaximum rated output power such as seventy-five watts DC, the surfacetemperature of the case 300 is less than one hundred and forty degreesFahrenheit and preferably less than one hundred and twenty degreesFahrenheit when the unit is operated at the maximum rated power of, forexample seventy five watts DC. Having the openings defined on both thetop and the bottom permits the user to operate the power supply in boththe “right side up” and the “upside down” position with adequate aircirculation. The case may be made of any high impact suitable plastics,such as Lexan or ABF, and when the top and bottom portions are assembledtogether such as by a snap lock or a force fit, they define a chamber inwhich all of the components are housed. Also, the exact dimensions arenot critical, but preferably, the ratio of the top and bottom surfaceareas should be much greater than the thickness.

FIG. 5B shows a partial cross-section of top portion of the case 300. Inpreferred embodiments of the present invention, a thin layer 306 ofmaterial is connected to the bottom of the louvers 302 to cover theopenings 304 that lead into the interior of the case 300. The thin layer306 is thin enough to still allow heat to pass through the openings 304using ordinary convection. However, the thin layer 306 is thick enoughto prevent entry of liquids into the case 300, which could affectoperation of the power supply. In preferred embodiments, the thin layeris 1 to 3 mils thick. However, in alternative embodiments, thinner orthicker layers may be used, so long as the layer is thick enough toresist penetration of liquids into the case 300 and as long as the layeris thin enough to permit normal heat dissipation by convection. Inpreferred embodiments, the thin layer 306 is formed from a plasticmaterial, such as Lexan, ABF or the like from which the remainder of thecase is also formed. However, in alternative embodiments, the thin film306 may be formed from metals, composites, ceramics or other heatconductive and liquid resistant materials.

In an assembled unit, immediately beneath the top (and above the bottom(not shown)) of the case 300 are heat sinks such as those shown in FIG.6. Each heat sink, which comprises a thin sheet of thermally conductivematerial such as aluminum (which may be anodized) is configuredpreferably to fit precisely within the top or bottom portions of thecase and defines a number of cutouts. These cutouts may provideclearance for certain components to be directly cooled by air enteringthrough the openings 304 defined between the louvers 302 or may beprovided for clearance of the components mounted on the printed circuitboard (not shown). Preferably, whatever pattern of cutouts are formed inthe heat sink, the pattern should be positioned so that when the unit isassembled, the heat sink material should provide adequate coverage overthe openings in the case 300 to resist penetration of spilled liquidsinto the assembled unit. This allows the unit to comply withUnderwriters Laboratories and other safety standards. Alternatively, thetop and bottom heat sinks may cover the entire power supply circuitboard (not shown). Of course, other suitable materials besides aluminummay be used for the heat sinks. In preferred embodiments of the presentinvention, the undersides of the louvers are scalloped (either along thelength of the louver 302 or from side to side of the louver 302) toprovide an air gap between the louvers 302 and the heat sink to minimizeconduction of the heat from the heat sink to the material of the case300 and louvers 302.

As shown in FIG. 5B, the louvers 302 are spaced close together to formthe openings 304 so that the openings 304 have a relatively narrowwidth. The width and depth of the openings 304 are chosen so thatfingers cannot come into contact with either the thin layer 306 or theheat sinks under the thin layer 306. This minimizes the heat transfer tothe user so that the touch temperature of the unit appears lower thanthe actual temperature. In preferred embodiments, the openings 304 are 3to 5 mm, which is narrow enough to prevent the entry of fingers fromsmall children. However, in alternative embodiments, narrower or wideropenings 304 may be used, with the width being selected based upon theenvironment in which the power supply will be used.

FIG. 5C illustrates a partial cross-section of another embodiment of thelouvers in accordance with an embodiment of the present invention. Inthis embodiment, the louvers 310 are formed from a single piece ofmaterial with raised ridges 312 separated by depressions 314. Thedepressions are connected and secured to the heat sink 316 (such asthose shown in FIG. 6) by adhesives, snap fit, simple contact or thelike. The raised ridges 312 of the louvers 310 are spaced close togetherto form the depressions 314 so that the depressions 314 have arelatively narrow width. The width and depth of the depressions 314 arechosen so that fingers cannot come into contact with either the bottomof the depressions 314 or the heat sink 316. This minimizes the heattransfer to the user so that the touch temperature of the unit appearslower than the actual temperature. In preferred embodiments, thedepressions 314 are 3 to 5 mm, which is narrow enough to prevent theentry of fingers from small children. However, in alternativeembodiments, narrower or wider depressions 314 may be used, with thewidth being selected based upon the environment in which the powersupply will be used. To minimize the transfer of heat from the raisedridges 312, an air gap 318 is formed beneath an undersurface 320 of theraised ridges 312 and the heat sink 316. The air gap 318 acts as aninsulator so that the touch temperature of the case is lower than theactual temperature of the power supply heat sink 316. In preferredembodiments, the raised ridges 312 and the depressions 314 are formedfrom a plastic material, such as Lexan, ABF or the like from which theremainder of the case is also formed. However, in alternativeembodiments, the raised ridges 312 and the depressions 314 may be formedfrom composites, ceramics or other heat conductive resistant and liquidresistant materials.

FIGS. 7A and 7B show a schematic for the power supply circuit 800 withall resistance in ohms and all capacitance in microfarads unlessotherwise labeled. The power supply is formed on a multilayer printedcircuit board (not shown) having length and width dimensions that areonly slightly smaller than the exterior of the case and fit as preciselyas possible within the chamber of the case 300 sandwiched between theheat sinks to minimize movement after assembly. Further, as far aspossible, surface mount devices are used to minimize the verticaldimension and all coil cores are preferably planar, low profile cores.Optimally, parts having the smallest possible thickness should be used.

The power supply 800 includes an input circuit 810 that may be coupledto any AC power source preferably having a frequency of between about 50to 90 hertz and preferably having a voltage of between about 90 to 240Volts AC. This input circuit 810 may include a full wave bridgerectifier 812, a filter circuit 814 and a regulation circuit 816 toprovide an independent power supply for all integrated circuits used onthe primary side 824 of the circuit. For filtering purposes, the inputregulator circuit 816 may also include a center tapped coil 819 mountedon one of the exterior legs of the “E” planar core 822 of thetransformer 820. (Preferably, the planar “E” core of the type shown inFIG. 2 is used.) When the AC input voltage exceeds a predetermined rangesuch as one hundred and forty volts RMS, transistor Q9 in cooperationwith Zener diode VR1 will cooperate so that the center tap of the coil819 will be selected. This permits the output Vbias of the regulator tobe in an acceptable range for higher input voltages such as may becommon outside of the United States. The output Vbias is used forsupplying power to all of the internal integrated circuits on theprimary side 824 of the transformer 820, namely integrated circuits U1and U2. This permits these integrated circuits U1, U2 to continuefunctioning even if the DC output voltage from the power supply 800drops below the range necessary for the integrated circuits U1 and U2 tocontinue operating.

A controller integrated circuit U1 provides the four control signals forpowering the MOSFETs coupled to the two primary coils 825 and 827 withtheir center taps coupled to Vbias. The outputs of integrated circuit U1at pins 7 through 10 provide the control signals to a MOSFET drivercircuit U2 such that MOSFETs Q1, Q2, Q4 and Q5 provide the appropriatephase control as is described in connection with FIG. 8. Integratedcircuit U2 may be for example a 4468 available from Micrel, Teledyne andTelcom.

Each of power switching MOSFET transistor pairs Q1 and Q2, and Q4 and Q5are coupled to center tapped primary coils 825 and 827, respectively.These transistors preferably have heat sinks (not shown) coupled totheir cases, and/or these heat sinks may also be thermally coupled toone of the heat sinks mounted immediately below and immediately abovethe top and bottom heat sinks for better thermal control. Thecapacitance of the MOSFETs Q1, Q2, Q4 and Q5 and the inductance of thecoils 825 and 827 are selected to provide resonance at the frequency atwhich the drive signals are supplied, which may be about 1 MHz.Nonetheless, other frequencies may be used, for example, between a rangeof about 500 KHz to 2 MHz.

FIG. 8 shows a timing diagram of the signals at nodes L through Q shownon FIGS. 7A and 7B. The integrated circuit U1, as described in moredetail below, through feedback, provides MOSFET driving signals Lthrough O. The MOSFET driving signals provided to each primary winding,825 and 827 (i.e., L and M for primary winding 825 and N and O forprimary winding 827) are always one hundred eighty degrees out of phaseas shown in FIG. 8. However, the relative phase relationship of drivingsignal pair L and M for primary winding 825 with respect to drivingsignal N and O for primary winding 827 may be changed by the integratedcircuit controller U1 in the manner described below to provided theregulated DC output voltage at connectors 846 and 848. Maximum power isprovided when the pairs of driving signals are in phase with each other.It should be noted that while the control signal provided at pins 7through 10 are preferably at substantially a fifty percent duty cycle,the resistors R10 through R13 and the capacitors C10 through C13 combinewith the integrated circuit U2 to provide preferably driving pulses Lthrough O with a duty cycle of less than 50 percent. This ensures thatthe FETS in a pair (i.e., Q1 and Q2 for winding 825 and Q4 and Q5 forwinding 827) are never both on at the same time to provide zero resonantswitching and reduce power consumption.

Due to the zero volt resonant switching design of the circuit, MOSFETpair Q1 and Q2 are preferably never on the same time and MOSFET pair Q4and Q5 are preferably never on at the same time. MOSFET Q1 will turn onjust about when the voltage at node P, which is at the drain oftransistor Q1, reaches a minimum and will turn off immediately after thevoltage at the drain of transistor Q1, goes above that minimum level.Similarly, due to the phase relationship of drive signal pair L and M atnodes L and M, transistor Q2 will only be on when the voltage at thedrain is almost at the minimum. Transistor Q4 will also only be on whenthe voltage at node Q is virtually at its minimum and the transistor Q5will only be on when the voltage at its drain is nearly at its minimum.

It should be noted that the duty cycle of signals L through O isselected so that the waveforms P and Q are substantially trapezoidalwith clipping occurring by transistors Q1, Q2, Q4 and Q5. This permitsoperation of the circuit over a wider range of input voltages. However,in alternative embodiments, transistors Q1, Q2, Q4 and Q5 need not clipso that the waveshapes at the drains of these transistors aresubstantially sinusoidal. Alternatively, using a low enough frequencyfor the drive signals, a square wave on the drains of the actualtransistors could be used but would probably require larger cores.

For the secondary side 826 of the power supply circuit 800, a singlesecondary winding 840 is located at the magnetic summing node of thecore 822 (i.e., the center leg of the low profile “E” type core shown inFIG. 2). That secondary winding 840 is coupled to a rectifier circuit842 and then to an output filter 844 including a filter choke L2 toprovide the regulated DC output at connectors 846, 848 in the mannerdescribed below.

The center tap of the secondary winding 842 is coupled through a coil inthe filter coil L2 sharing a common core with the coil in the outputfilter 844. Through resistor R23, this center tap of winding 842provides a current sense input to a summing amplifier U3A. A voltagesense of the output DC regulated voltage Vout is provided to anamplifier including amplifier U3C. The sensed voltage signal at theoutput of amplifier U3C is provided to the summing amplifier U3A throughamplifier circuit U3B to provide the feedback necessary for the desiredregulation of the DC output.

The output of the summing amplifier U3A is provided through an emitterfollower transistor Q7 to the center tap of the secondary side 826 ofthe feedback transformer 850. This transformer is magnetically isolatedfrom the transformer 820. The signal at the center tap of transformer850 amplitude modulates a carrier signal provided by winding 852provided on the same exterior leg of the core 822 as primary winding827. Preferably also, this should be the opposite exterior leg of thecore 822 on which coil 819 and winding 825 are mounted.

The primary side 824 coil of transformer 850 provides an amplitudemodulated feedback signal that has an amplitude envelope. A diodedetector comprised of diode CR5 and resistor R17 strip the carrier away,leaving the amplitude envelope as a feedback control signal to the VMODinput (pin 1 of U1) to provide the feedback useful for altering of thephase relationship between the drive signal pairs of signals L and M onthe one hand, and signals N and O, on the other hand to regulate the DCpower supply output at connectors 846, 848.

With the current control connector 860 and the voltage control connector862 left unconnected (as shown), amplifiers comprising U3B and U3D alongwith the current and voltage sense signals cause the integrated circuitU1 to control the phase relationship between the drive signal pairs Land M, on the one hand, and N and O, on the other hand, to provide aconstant power supply until the output voltage drops below about tenvolts. Then, due to the feedback signal at pin 1 of the controller U1,the integrated circuit controller U1 controls the relative phaserelationship between the pair of drive signals L and M, on the one hand,and N and O, on the other hand, to provide a constant current sourcedown to a minimal voltage, which is preferably less than about one volt.

It should also be noted that the Vcc used by the amplifiers U3A throughU3D in the integrated circuit U3 and the voltage regulator U4 togenerate the +5 volts used in the control circuit (e.g. comprisingamplifiers U3B, U3C and U3D) is supplied by a rectifier circuit 854. Therectifier circuit 854 is also coupled to secondary coil 852.

FIG. 9 shows a block diagram 900 of the controller integrated circuitU1. Pins 13, 14, and 15 cooperate together along with externalcomponents R3, R4, R5 and R6 to set the operational frequency of theoscillator 902 to be preferably at 2 MHz, although other frequencies maybe selected. An output of the oscillator 902 is coupled to an internalcapacitor 901 to provide a triangle signal labeled Ramp on FIGS. 10A and10B while another output of the oscillator 902 is a 2 MHz square wavecoupled to exclusive OR gate 904 and the clock input of a D flip flop907. A Schmitt trigger comparator 906 compares the feedback signal VMODat pin 1 with the ramp signal as is shown in FIGS. 10A and 10B. In FIG.10A, the VMOD signal, which is the envelope of the feedback signal fromthe feedback transformer 850 is at the maximum level, while in FIG. 10B,the VMOD signal is somewhat less than the maximum. As can be seen inFIGS. 10A and 10B, the comparator 906 cooperates with the D flip flop907, the exclusive OR gate 904, and the associated logic gates 908 togenerate one shot control signals J and K. As can be seen by comparingFIG. 10A, when VMOD is at a maximum, the one shot drive signals J and Kare controlled so that both one shot control signals go high at the sametime. When the amplitude of VMOD drops below the maximum, the timing ofthe one shot control signal J is retarded and the timing of the one shotcontrol signal K is advanced. These one shot control signals J and K areprovided to one shot circuits 920 and 930 within the controller circuitU1, which have dual outputs VA and VC and VB and VD respectively. Theone shots 920 and 930 trigger on the rising edge of signals J and Krespectively, and the durations to the falling edge of the controlsignals J and K are irrelevant provided that they fall before the oneshots need to be retriggered. Due to the inclusion of inverters 922 and932, the output pair of signals VA and VC and VB and VD areapproximately one hundred and eighty degrees out of phase. It shouldalso be noted that the external capacitor C7 and resistor R7 are coupledto pins 5 and 4 of the controller U1 to control the duration of theoutput pulses at the one shot 920 and the one shot 930 to trigger themfor the same duration. Further, these component values are selected tobe as near as possible to provide a fifty percent duty cycle on theoutputs L through O of the MOSFET driver circuit U2 at the frequency ofoperation.

The controller circuit U1 also includes a reference voltage generator940 that provides the reference voltage for the over voltage protectioncircuit 942 and the comparator 944. As shown in FIG. 7, an over voltageprotection circuit 830 having a coil 832 is located at or near thesumming node of the E block core 822. The value of the components withinover voltage protection circuit 830 are selected such that if the outputvoltage DC Output goes above a predetermined threshold, siliconcontrolled rectifier (SCR) Q3 will fire, shunting the Vbias to ground.This will cause the integrated circuits U1 and U2 to cease operating,thereby shutting down the output until the unit is recycled bytemporarily removing the AC input voltage.

Thus, a small, highly efficient form factor power supply has beendisclosed that may be readily mounted within a small container having athickness of 0.436 inches or less and having dimensions suitable forholding in a typical shirt pocket or calculator pocket in a brief caseat high power levels of up to about 75 watts DC output with a surfacetemperature of about 140 degrees Fahrenheit at the surface. Thicknessesof less than 0.436 inches may be attainable if thinner electrolytic orother types of filtering capacitors can be obtained using standardproduction techniques. Alternatively, a thinner case may be obtained bymaximizing coupling of heat generating components to the heat sinks withmaximum air flow through the openings defined by the louvers 302 and bymaking the top and bottom surface areas of the case larger. Regulationof the output voltage may be readily attained. Still further, thesecondary coil can be positioned where the magnetic flux induced in thecore from the two primary coils destructively interfere with each otherand where the phase of the two driving signals is approximately onehundred eighty degrees out of phase at maximum output. In furtheralternatives, cooling methods other may be used, such as small electricfans, thermal-electric coolers or the like, to permit smaller formfactor power supply configurations. Other alternatives will be readilyapparent to those of skill in the art. It should be noted that inalternative embodiments, the various resistors, capacitors, frequenciesand inductors may be different and other types of integrated circuitsmay also be used.

FIGS. 12–16 illustrate an improved transformer core 1010 in accordancewith an embodiment of the present invention. FIG. 12A shows a top planview of the transformer core 1010, which is formed by a base plate 1012,a secondary leg 1014 and a pair of primary legs 1016 and 1018. Thesecondary leg 1014 and the primary legs of the transformer 1010 may bebosses attached to the base plate 1012 by welds, magnetically permeableadhesives, or the like, or the entire assembly may be molded usingmagnetically permeable powder. FIGS. 12B and 12C show two side planviews of how the transformer legs 1014, 1016, and 1018 are positioned onthe base plate. FIG. 13A shows a top plan view of a transformer cap1020, which is secured to the legs 1014, 1016, and 1018 of thetransformer core 1010 to complete the transformer core once the bosseshave been inserted through cutouts. The transformer legs 1014, 1016, and1018 are secured to the transformer cap 1020 by magnetically permeableadhesives, welding or the like. FIGS. 13B and 13C show side plan viewsof the transformer cap 1020.

In preferred embodiments, the transformer core 1010 and transformer cap1020 are formed from a ferrite material. The operational frequency rangeof the core is from about 0.5 to 1.0 MHZ. Also, the initial magneticpermeability is preferably 1400±20%. In addition, the saturation fluxdensity may be 5300 gauss, and the Curie temperature may be 250 degreesCentigrade. The core loss while operating at a frequency of 1 MHZ shouldpreferably be approximately 500 KW/m at 500 gauss. In other embodiments,different core parameters may be used.

In the disclosed embodiments, the base plate 1012 and the transformercap are dimensioned to be 1.260×1.260×0.075 inches. The secondarytransformer leg 1014 is dimensioned to be 0.800×0.200 by 0.060 inches,and each primary transformer leg is 0.133×0.700×0.060 inches. Thesecondary transformer leg 1014 is positioned away from the primarytransformer legs 1016 and 1018, as shown in FIGS. 12A–12C, to maximizethe cross-sectional area of each of the transformer legs (i.e., thelength and width of the transformer legs). This maximizes a ratio of thecross-sectional area of the transformer legs to the windings, therebyrequiring less windings for the same magnetic coupling. Fewer windingsmeans less area of a layer of a circuit board may be used so that thenumber of layers on the circuit board may be minimized. The improvedtransformer core also provides this maximized ratio while maintainingthe ratio of the secondary to the primary windings at a constant value.However, in alternative embodiments, slightly different dimensions forthe core parts may be used. Also, as described in the previousembodiments, the secondary coil is still positioned at a summing pointof the primary coils.

FIG. 14 shows a printed circuit card layer 1030 without secondary orprimary cores attached and having cutouts 1014′, 1016′ and 1018′ toallow the corresponding transformer legs 1014, 1016 and 1018 to passthrough the printed circuit board. FIG. 15 shows another printed circuitcard layer 1030″ in which a secondary coil pattern 1040 surrounding thecut-out 1014′ for the secondary transformer leg 1014. FIG. 16 showsstill another printed circuit card layer 1030′ in which primary coilpatterns 1042 and 1044 surround the cut-outs 1016′ and 1018′ for the toprimary transformer legs 1016 and 1018, respectively.

FIGS. 17–22 illustrate an alternative embodiment using two transformercores 1110 in accordance with the present invention. FIG. 17A shows atop plan view of bottom portion of the transformer core 1110, which isformed by a base plate 1112, a central leg 1114 and a pair of peripherallegs 1116 and 1118. The central leg 1114 and the peripheral legs of thetransformer 1110 may be bosses attached to the base plate 1112 by welds,magnetically permeable adhesives, or the like, or the entire assemblymay be molded using magnetically permeable powder. FIGS. 17B and 17Cshow two side plan views of how the transformer legs 1114, 1116, and1118 are positioned on the base plate 1112. FIG. 18A shows a top planview of a transformer cap 1120, which is secured to the legs 1114, 1116,and 1118 of the transformer core 1110 to complete the transformer coreonce the bosses have been inserted through cutouts. The transformer legs1114, 1116, and 1118 are secured to the transformer cap 1120 bymagnetically permeable adhesives, welds or the like. FIGS. 18B and 18Cshow side plan views of the transformer cap 1120.

In preferred embodiments, the transformer core 1110 and transformer cap1120 are formed from a ferrite material that has properties andcharacteristics that are similar to those of the embodiment with thetransformer core 1010, discussed-above.

In the disclosed embodiments, the base plate 1112 and the transformercap 1120 are dimensioned to be 1.113×1.113×0.075 inches. The centraltransformer leg 1114 is dimensioned to be 0.300×0.300 by 0.060 inches,and each peripheral transformer leg is 0.075×0.630×0.060 inches. Thecentral transformer leg 1114 is positioned away from the peripheraltransformer legs 1116 and 1118, as shown in FIGS. 17A–17C, to maximizethe cross-sectional area of the central transformer leg 1114 (i.e., thelength and width of the central transformer leg). This maximizes a ratioof the cross-sectional area of the central transformer leg 1114 to thewindings, thereby requiring less windings for the same magneticcoupling. Fewer windings means less area of a layer of a circuit boardmay be used so that the number of layers on the circuit board may beminimized. The improved transformer core also provides this maximizedratio while maintaining the ratio of the secondary to the primarywindings at a constant value. Also, as described in the previoustransformer core 1010 embodiment, the secondary coil is still positionedat a summing point of the primary coils.

FIG. 19 shows a printed circuit card layer 1130A defining a secondarycoil 1040′ and having cutouts 1114′, 1116′ and 1118′ and cutouts 1114″,1116″ and 1118″ to allow the corresponding transformer legs 1114, 1116and 1118 of two transformer cores 1110 to pass through the printedcircuit board. The secondary coil pattern 1140′ passes around bothcentral leg cutouts 1114′ and 1114″ to magnetically couple the secondarycoil pattern 1040′ with the summing point of two primary coils (seeFIGS. 20 and 21). FIG. 20 shows another layer 1130B of the printedcircuit card in which two primary coil patterns 1142′ and 1142″ surroundthe corresponding central cutout 1114′ and 1114″, respectively. FIG. 21shows another printed circuit card layer 1130C in which two additionalprimary coil patterns 1144′ and 1144″ surround the corresponding centralcutout 1114′ and 1114″, respectively. It should be noted that primarycoil patterns 1144′ and 1144″ are coupled to corresponding primary coilpatterns 1142′ and 1142″ to form the two primary coils that drive thesecondary coil. FIG. 22 shows still another printed circuit card layer1130D in which a secondary coil pattern 1140″ surrounds thecorresponding central cut-out 1114′ and 1114″, respectively. It shouldbe noted that secondary coil pattern 1140′ is coupled to thecorresponding secondary coil pattern 1140″ to form the secondary coilthat is coupled to the primary coils. Finally, it should be pointed outthat the ancillary coil patterns 1146 surrounding the peripheral legs1116′ and 1116″ are provided to produce a signal useful for protectingthe circuit from over voltage.

The applicant has found that this characteristic power and current curveprovides good charging of lithium ion, nickel metal hydride, nickelcadmium and other rechargeable batteries. Thus, the small form factorpower supply is capable of supplying sufficient power to a personalcomputer or the like, even when the batteries are thoroughly discharged.The constant current at the output connectors 846, 848 can provideminimal voltages down to about less than one volt because the controllerU1 can attain relative phase shifts between the drive signal pairs tobetween about one degree to one hundred eighty degrees (i.e., signal Nlags signal L between about one degree to one hundred eighty degrees andsignal O and lags signal M between about one degree and one hundredeighty degrees). Thus, as shown in FIG. 11, if one were to draw a powerversus output current curve and an output voltage versus output currentcurve of such a power supply, the slope of the output voltage curve isrelatively constant until the output current reaches approximately 2.0amperes, then slopes down to 10 volts at which time the output currentis essentially constant at approximately 3.6 amperes for voltages under10 volts. The output power curve increases relatively linearly until thecurrent level reaches approximately 2.2 amperes, at which time theoutput power curve tends to level off until the current reaches itmaximum value of approximately 3.6 amperes. Therefore, the power supplyis capable of providing constant current to the personal computer or thelike, even if the battery is only capable of producing a fraction of avolt. This power curve is determined as a result of the selectedamplifier configuration associated with integrated circuit U3, which maybe an LM 324 on the secondary side 826. The predetermined limit may beas high as 75 watts DC for a power supply having an upper and lowersurface area within the case 300 of about 14 square inches and athickness of about 0.436 inches or less so that the ratio of the top orbottom surface areas to the thickness is about 30:1.

However, the circuit can readily be programmed to provide otherpower/current characteristics, such as the power characteristics for laptop computers, appliances, cellular or portable telephones, notebookcomputers, game systems or the like. This may be accomplished bycoupling additional resistors to ground and/or +5 volts (generated by avoltage regulator U4) to the current control and voltage control inputs.FIG. 7B shows such an embodiment, with resistors R860 and R862 connectedbetween Vref (produced by the voltage regulator U4) and current controlinput 860 and voltage control input 862, respectively. In embodiments ofthe invention, multiple resistors such as resistors R860 and R862 may beselectively connected between ground or a regulated voltage, such as the+5 volts produced by the voltage regulator U4 (as shown in FIG. 7C), andthe current control input 860 or voltage control input 862. In theembodiment shown in FIG. 7C, a switch S1 may be used to select which oneof the resistors R860 a, R860 b and R860 c is connected between theregulated voltage and a control input CI, which may be a current controlinput 860 or a voltage control input 862, in order to control the outputvoltage or output current of the power supply. The switch S1 may be amechanical switch, a transistor switch, a logic gate or the like and mayreceive an input signal to control which of the resistors R860 a, R860 band R860 c is selected.

In embodiments of the invention, the power supply may be used to power avariety of electrical appliances with varying input voltage and inputcurrent requirements by attaching various connectors to interface withthe output connection terminal of the power supply and the inputconnection terminal of the appliance. These connectors may have a commontype of input interface adapted to mate with the output connectionterminal of the power supply but differing types of output interfacesadapted to mate with the input terminals of particular appliances. Atthe same time, a resistor from among resistors R860 a, R860 b and R860 cmay be selected to provide a particular output voltage or output currentrequired by a particular electrical appliance.

In embodiments of the invention, a resistor indicator (e.g., a color orsymbol element associated with the connection of a selected resistor)may correspond to a connector characteristic to ensure that the selectedconnector and selected resistor match a particular appliance to bepowered. For example, where a particular type of cellular phone is to bepowered, the connector corresponding to that type of phone may becolored blue. Text associated with the mechanical switch settingcorresponding to the resistor to be connected for powering that type ofphone may also be colored blue. The user may be instructed to match thecolor of the mechanical switch setting to the color of the connectorfitting the appliance input connection terminal. Alternatively, theconnector and switch setting may both be marked with a symbol associatedwith a cellular telephone, the connector may be marked with anindication of a corresponding switch setting (such as a switch positionnumber), a light may be activated or changed in color when the selectedconnector and selected resistor match, or the like.

In embodiments of the invention, resistors and/or a resistor-and-switchcombination similar to the one shown in FIG. 7C may be incorporated intoconnectors that interface between the power supply and the electronicappliance as described hereinafter. As in embodiments in which a switchis included as part of the power conversion circuit, the switch may bemechanical or electronic (e.g., a transistor-based switch or logicgate). In embodiments in which an electronic switch is used, theresistor selection may be based upon an input signal received by theswitch.

Alternatively, as shown in FIG. 23, the current control input 860 andvoltage control input 862 (see FIG. 7) can be coupled through a cable882 to control circuits 884 commonly contained within the rechargeablebatteries 886 coupled to the DC output connectors 846 and 848. Thesecontrol circuits 884 may contain amplifiers 888, resistors 890, digitalto analog converters or any other analog signal generator that may becoupled to the current and voltage control inputs 860, 862 through thecable 882 coupled to the battery terminals for charging. This wouldpermit the controller in the battery programmatically to regulate thevoltage and the current provided at the DC output to minimize rechargingtime based upon the known characteristics of the battery.

Preferably, the programming of the small form factor power supply iscarried out using either resistive programming or analog programming.However, in alternative embodiments, other programming methods may beemployed, such as digital or microprocessor controlled programming (withor without resistance ladder networks), with the type of programmingtechnique being dependent on the power requirements of the device.

FIG. 24 is a schematic of a programming circuit in accordance with anembodiment of the present invention that is used to resistively programthe power supply to produce between 0 and 16 volts, and FIG. 25 is aschematic of another programming circuit in accordance with anembodiment of the present invention that is used to resistively programthe power supply to produce between 16 and 18 volts. FIG. 26 is an endview of a connector that mates with the small form factor power supply(shown in FIGS. 3 and 7) and is useable to program the small form factorpower supply, as shown in FIGS. 24 and 25.

As shown in FIGS. 24 and 25, the power supply may be programmed remotelyto provide the required power at voltages between 0 to 18 volts usingvarious external cables having built in resistances that program thepower supply to output the required power level (i.e., voltage andcurrent). This method allows the small form factor power supply to beprogrammed for any value of voltage and/or current by connecting aresistor from the voltage and/or current programming pins (e.g., pins 1and 4) to ground (e.g., pin 3) as shown in FIG. 24, or from the voltageprogramming pin (e.g., pin 1) to V_(OUT) (e.g., pin 4) for voltagesabove 16 volts as shown in FIG. 25.

To program the voltage between zero and 16 volts, as shown in FIG. 24,the following formula is used:

$R = \frac{10\left( V_{OUT} \right)}{16\left( V_{OUT} \right)}$

where R=the programming resistance between pins 3 and 4 (in Kohms); andwhere V_(OUT)=output voltage.

To program the output voltage between 16 and 18 volts, as shown in FIG.25, the following formula is used:

$R = \frac{10\left( V_{OUT} \right)}{V_{OUT} - 16}$where R=the programming resistance between pin 2 and 4 (in Kohms); andwhere V_(OUT)=output voltage.

To program the output current between 0 and 3.6 amps, as shown in FIGS.24 and 25, the following formula is used:

$R = {\left( \frac{I_{OUT} + 4.133}{3.647 - I_{OUT}} \right) \times 7.823}$where R=programming resistance between 1 and 3 (in Kohms); andwhere I_(OUT)=output current

In another method, analog programming of the small form factor powersupply is used. This method allows the small form factor power supply tobe programmed for any value of voltage and/or current by providing ananalog voltage signal from the respective programming pins and ground.

To program the output voltage between 0 and 18 volts, the followingformula is used:

where

$V_{P} = \frac{V_{OUT}}{3.2}$V_(P)=programming voltage applied to pin 4 with respect to pin 3; andwhere V_(OUT)=output voltage.

To program the output current between 0 and 3.6 amps, the followingformula is used:

$I_{P} = {\left( \frac{I_{OUT}}{1.238} \right) + 1.68}$where I_(P)=programming voltage applied to pin 1 with respect to pin 3;andwhere I_(OUT)=output current.

In addition, the power supply may interface with a programmable currentgenerator interface, such as an MC33340 fast charge battery controllermanufactured by Motorola, Inc. of Schaumberg, Ill. or a BQ2002Cmanufacture by Benchmarq, Dallas, Tex. This allows the cable to directlyinterface with the power supply, while performing the functions ofcharge termination or trickle charging. In preferred embodiments, thereis a ½ power factor available. The cable includes a chip that is adaptedto work with a specific device, such as a cellular telephone, laptopcomputer or the like, so that the charging characteristics of the powersupply are altered as needed by simply changing cables. Alternatively, ageneric cable can be used and an adapter may be connected to the powersupply between the cable and the power supply that contains differentresistors that program the power supply to provide a desired powersupply. Typically, precise charge termination is difficult to detectwhen the battery reaches saturation. Thus, preferred embodiments of thepresent invention detect the knee of the power curve shown in FIG. 11and reduce the current to deliver at a more steady rate.

FIGS. 27( a)–34(c) show various cables with connectors in accordancewith embodiments of the present invention that program the small formfactor power supply for supplying power to different devices. Thesecables have a connector 1500 for connecting with the small form factorpower supply and use various configurations of resistances and wireconnections to program the small form factor power supply to work withvarious devices. In these figures, NC=no connection, +DC=V_(OUT) (e.g.,from pin 2 of FIG. 26), CC=I_(program) (e.g., from pin 1 of FIG. 26),VC=V_(program) (e.g., from pin 4 of FIG. 26), and GND=ground (e.g., frompin 3 of FIG. 26). FIGS. 27( a)–27(c) show views of a cable 1502 havinga connector 1504 for use with IBM computers, such as the “ThinkPad” orthe like. No resistances are provided in the connectors 1500 and 1504,since the IBM computers provide their own power regulation, and the pinsfrom the small form power supply (e.g., FIG. 27( c)) are converted to acompatible connector and pin out, as shown in FIG. 27( b). FIGS. 28(a)–28(c) show views of a cable 1506 having a connector 1508 for use withIBM computers, such as the “ThinkPad” or the like, and for Compaqcomputers, such as the Armada or the like. No resistances are providedin the connectors 1500 and 1508, since the IBM and Compaq computersprovide their own power regulation, and the pins from the small formpower supply (e.g., FIG. 28( c)) are converted to a compatible connectorand pin out, as shown in FIG. 27( b). FIGS. 29( a)–29(c) show views of acable 1510 having a connector 1512 for use with for Compaq computers,such as the Contura, LTE or the like, Toshiba computers, such as theSatellite and the Protege, Gateway computers, such as the Solo, andHitachi computers, such as the C120T and the like. Either the connector1500 or the connector 1512 use resistances between pins 2 and 4 of thesmall form factor power supply to program the small form factor powersupply. FIGS. 30( a)–30(b) show views of a cable 1514 that does not havea connector. The end 1516 of the cable 1514 is left with bear wires tobe configured to work with various computers that don't use theresistances or connectors shown in the other cables. Since the cable1514 has no end connector, it can be wired to match various computerconfigurations. FIGS. 31( a)–31(c) show views of a cable 1518 having aconnector 1520 for use with another configuration of a computer. Eitherthe connector 1500 or the connector 1520 use resistances between pins 1,3 and 4 of the small form factor power supply to program the small formfactor power supply. FIGS. 32( a)–32(c) show views of a cable 1522having a connector 1524 for use with Hewlett Packard computers, such asthe Omnibook or the like. Either the connector 1500 or the connector1524 use resistances between pins 3 and 4 of the small form factor powersupply to program the small form factor power supply. FIGS. 33( a)–33(c)show views of a cable 1526 having a connector 1528 for use with Toshibacomputers, such as the Tecra or the like. Either the connector 1500 orthe connector 1528 use resistances (having a different value than thosefor cable 1522) between pins 3 and 4 of the small form factor powersupply to program the small form factor power supply. FIGS. 34( a)–34(c)show views of a cable 1530 having a connector 1532 that is designed tobe a universal cable that accepts various connector ends that can matewith different device. No resistances are provided in the connectors1500 and 1532, since the cable 1530 is converted to be compatible withvarious devices based on the connector adapters connected to theconnector 1532.

FIGS. 35( a)–40(c) show various connector adapters for use with thefemale connector 1532 of the cable 1530 shown above in FIGS. 34(a)–34(c). FIGS. 35( a)–35(c) show a connector adapter 1534 having a maleconnector 1536 for connecting with the connector 1532 and has an endconnector 1538 that converts the generic cable 1530 of FIGS. 34(a)–34(c) to correspond to the cable 1502 shown in FIGS. 27( a)–27(c).FIGS. 36( a)–36(c) show a connector adapter 1540 having connectors 1536and 1542 that convert the generic cable 1530 of FIGS. 34( a)–34(c) tocorrespond to the cable 1506 shown in FIGS. 28( a)–28(c). FIGS. 37(a)–37(c) show a connector 1544 having connectors 1536 and 1546 thatconvert the generic cable 1530 of FIGS. 34( a)–34(c) to correspond tothe cable 1510 shown in FIGS. 29( a)–29(c). FIGS. 38( a)–38(c) show aconnector adapter 1548 having connectors 1536 and 15505 that convert thegeneric cable 1530 of FIGS. 34( a)–34(c) to correspond to the cable 1518shown in FIGS. 31( a)–31(c). FIGS. 39( a)–39(c) show a connector adapter1552 having connectors 1536 and 1554 that convert the generic cable 1530of FIGS. 34( a)–34(c) to correspond to the cable 1522 shown in FIGS. 32(a)–32(c). FIGS. 40( a)–40(c) show a connector adapter 1556 havingconnectors 1536 and 1558 that convert the generic cable 1530 of FIGS.34( a)–34(c) to correspond to the cable 1526 shown in FIGS. 33(a)–33(c).

FIGS. 41( a) and 41(b) illustrate a block diagram and a schematic of aninterface for providing power to more than one device at a time. Asshown in FIG. 41( a), a small form factor power supply 2000 is connectedthrough a cable 2002 to an interface 2004 that supports more than onedevice at a time by the power supply. The interface 2004 can support twoor more devices, with the number of devices being dependent on thenumber of power output ports. The power to each device is controlled bycable connections to each device, such as the cables and connectorsdescribed above in FIGS. 27( a)–40(c). As shown in FIG. 41( b), theinterface 2004 receives the cable 2002, which has a first voltage wire2006 providing a first voltage V1 and a second voltage wire 2008providing ground G. This is generally connected to the primary device.Additional devices are connected to wires 2006 and 2008 through taps2010 and 2012. Tap 2012, if necessary, feeds into a voltage regulator tochange the voltage to that desired by the device and outputs a secondvoltage on wire 2014 and ground on wire 2016. In alternativeembodiments, the additional regulator may be provided in the cable usedfor each device.

FIGS. 42–44 show various perspective views of a small form factor powersupply 3000 that has been configured for use with portable telephoneequipment in accordance with an embodiment of the present invention(note: these drawings are from 3-Dimensional CAD drawings and the manylines in the drawings indicate curves on the small form factor powersupply and do not represent surface features). FIGS. 45 and 46 showperspective views of the small form factor power supply 3000 connectedto a cellular telephone battery and telephone. The small form factorpower supply 3000 is directed to charging portable telephone batteries.It has a housing 3002 similar to that described above and uses thecharging circuitry described above. However, in alternative embodiments,different charging topologies may be used, depending on the chargingenvironment, the battery type and the weight requirements of the smallform factor power supply. Embodiments of the small form factor powersupply can be adapted to work with telephones manufactured by Audiovox,Ericsson/GE, Fujitsu, JRC, Mitsubishi/Daimondtel, Motorola, Murata,NECK, Nokia, Novatel, Oki, Panasonic, Sony, Uniden, AT&T, Tandy,Pioneer, JVC or the like. Also, the small form factor power supply canbe used with a wide variety of portable telephone equipment, such ascordless telephones, cellular telephones, radio telephones, PCStelephones and the like.

The housing 3002 of the small form factor power supply 3000 includes afoldable AC plug 3004 that is adapted to plug into a standard electricalsocket (not shown) to receive power, from standard lines, that is to betransformed and supplied to an attached device. Alternative embodimentsmay use different plugs to handle different voltages and/or differentcountry's electrical socket and power configurations. As shown in FIG.42, the AC plug 3004 folds into a recess 3006 when not being used. TheAC plug 3004 is unfolded by engaging and rotating a tab 3008 to rotatethe AC plug 3004 out of the recess 3006. In alternative embodiments, theAC plug may be spring loaded and utilize a catch to lock the AC plug inthe folded down position and once the catch is released the springrotates the AC plug into the unfolded position. The AC plug 3004 mayinclude detentes or use other methods to maintain the AC plug 3004 inthe folded or unfolded position. Once unfolded, the AC plug 3004 can beinserted into the socket, and the housing 3002 generally hangs downagainst a wall for stability and support. In alternative embodiments,the AC electric plug may be recessed and fixed in the housing of thesmall form factor power supply 3000 to receive an electrical cord thatis attached between the AC plug and an electric socket.

As shown in FIGS. 42 and 43, a power output 3010 is adapted to fold outand includes a plurality of contacts 3012 that mate with thecorresponding contacts (not shown) on a portable telephone equipmentbattery 3011. In preferred embodiments, the contacts 3012 of the smallform factor power supply 3000 are placed in electrical contact with thecontacts on the back of the battery 3011. Alternatively, when thebattery 3011 is not coupled to portable telephone equipment, thecontacts 3012 of the small form factor power supply may be placed inelectrical contact with the contacts of the battery 3011 that providepower to the portable telephone equipment. To unfold the power output3010, the user pushes the power output 3010 through a port 3014 to forcethe power output 3010 to rotate down about a hinge 3016. The poweroutput 3010 may be spring loaded with a catch, detentes or other methodsto lock the power output 3010 in the folded or unfolded position. Inalternative embodiments, the small form factor power supply 3000 may usea recessed connector that connects to either the portable telephoneequipment or battery using a cable such as described above and below.

The small form factor power supply 3000 also has support legs 3018 thatinclude ends with guide tabs 3020. The guide tabs 3020 are shaped toengage with channels 3021 on the portable telephone equipment battery3011 to hold the battery 3011 in electrical contact with the small formfactor power supply 3000 during charging. The support legs 3018 are alsocapable of holding a portable telephone connected to the battery 3011,as shown in FIGS. 45 and 46. The support legs 3018 are rotated out whenthe small form factor power supply 3000 is to be connected to a battery3011. To attach the small form factor power supply 3000, as shown inFIGS. 45 and 46, the user slides the battery 3011 to engage the channels3021 of the battery 3011 with the guide tabs 3020 of the support legs3018. The user then slides the battery 3011 back, until it is stoppedand contacts the power output 3010. In preferred embodiments, each ofthe support legs 3018 rotates independently of the other to simplifymanufacturing and reduce complexity of the small form factor powersupply 300. However, in alternative embodiments, the support legs 3018may rotate out together as a unit and/or rotate out when the poweroutput 3010 is rotated.

In preferred embodiments, the small form factor power supply 3000 iscapable of charging most telephone equipment batteries in less than 15minutes. However, the actual charging time will vary based on the sizeof the battery and the battery chemistry. Most batteries (providingbetween 1 to 15 hours of high power operation) charge in 5–30 minutes.The small form factor power supply 3000 includes a temperature sensorthat is included in the small form factor power supply control chip tocharge the battery as described above. This temperature sensor allowsthe small form factor power supply to determine the proper charging ratefor a battery and avoid generating undue heat by overcharging orcharging at too high a rate. In further embodiments, the small formfactor power supply can be used to power the portable telephoneequipment simultaneously with charging of an attached battery.Alternatively, the small form factor power supply may be able to powerthe portable telephone.

In the embodiment of FIGS. 42–46, the AC plug 3004, the power output3010, and the support legs 3018 are all designed to be folded in whenthe small form factor power supply 3000 is not in use. This minimizesthe profile of the small form factor power supply when it is not in useand makes it easier to transport. In alternative embodiments, the ACplug, the power output and the support legs may be formed or maintainedin the unfolded position, where the smaller profile is not needed or anadvantage.

FIG. 47-50 show a perspective and plan views of a small form factorpower supply adapter connector 4000 for use with portable telephoneequipment in accordance with embodiments of the present invention (note:these drawings are from 3-Dimensional CAD drawings and the many lines inthe drawings indicate curves on the small form factor power supply anddo not represent surface features). The adapter connector 4000 has ahousing 4001 that includes a connector 4002 configured to mate with theconnector .1532 of cable 1530 shown in FIGS. 34( a)–34(c). This adapterconnector provides an upgrade path for users that already posses a smallform factor power supply, as described above.

As shown in FIGS. 47–50, the adapter connector 4000 includes a pluralityof contacts 4006 for connecting with corresponding contacts (not shown)on a portable telephone equipment battery. The housing 4001 may alsocontain additional circuitry or electronics needed to properly program asmall form factor power supply to charge a portable telephone equipmentbattery.

The adapter connector 4000 includes leg supports 4008 with guide tabs4010 that engage with channels on a battery (similar to those shown inFIGS. 45 and 46 above). To secure the adapter connector 4000 to abattery, an end clip (not shown) attached to the adapter connector 4000by elastic straps (not shown), or the like. The elastic straps arethreaded through eyelets 4011 so that the adapter connector 4000 can notslip off the battery. In the illustrated embodiment, the leg supports4008 are foldable about a hinge 4012 to reduce the profile of theadapter connector 4000 when not in use and/or when being transported. Inalternative embodiments, the support legs 4008 may be formed in a fixedopen position.

The small form factor power supplies described above are capable ofcharging various different types of batteries, such as NiCad and NiH.However, in alternative embodiments, the small form factor powersupplies may charge batteries using Zinc air, Lead acid, alkaline or thelike. The power supply may also be used to charge Lithium ion batteries,although a different control chip or circuitry may be required to handlethe unique charging requirements of these batteries.

While embodiments of the present invention are directed to a form factorpower supply in particular, other embodiments of the present inventionare directed more generally to power supplies which are programmable toprovide power to any one of a number of electronic devices havingdiffering input power requirements. The embodiment discussed above withreference to FIGS. 7A and 7B includes a power supply which isprogrammable to provide a power output at a terminal 846 at a suitableoperational current or operational voltage associated with theparticular electronic device which is to be powered. The appropriateprogramming signal can then be applied to either terminal 860 or 862using, for example, an appropriate connector associated with the deviceto receive power as discussed above with reference to FIGS. 23 through41.

FIG. 51 illustrates a schematic of an alternative embodiment of aprogrammable power supply 5000 which receives input power from a DCpower source and controls the output power using a pulse widthmodulation technique. Resistances are expressed in ohms and capacitancesare expressed in micro farads unless noted otherwise. A DC input sourcesuch as a 12 volt automobile cigarette lighter is provided acrossterminals 5011 and 5012. Other embodiments may be adapted to receivepower from other DC sources such as, for example, a DC power source inthe passenger compartment of an airplane at different voltages such as15 volts. The input circuitry of the embodiment shown in FIG. 51 differsfrom the embodiment shown in FIGS. 7A and 7B by, among other things,replacing the input transformer and full bridge rectifier circuit with asingle inductor L21 in a Buck regulator topology.

A transformer T21 includes a primary coil 5002 and a secondary coil5004. The primary coil 5002 receives current from the inductor L21. Thiscurrent through the primary coil 5002 induces an output current throughthe secondary coil 5004 to an output terminal 5864. A switch transistorQ61 controls the current through the primary coil 5002 to affect theoutput current induced in the secondary coil 5004. An integrated circuitU21 opens and closes the switch transistor Q61 to pulse width modulatethe current through the primary coil 5002. The integrated circuit U21may be an integrated circuit number UC3845 sold by Unitrode. Theintegrated circuit U21 is preferably configured to provide fixed widthpulses at an output pin 6 during which the switch transistor Q61 isclosed to provide a pulse of current through the primary coil 5002. Theintegrated circuit U21 then receives an input signal at a terminal 2 tocontrol the duty cycle of the pulse signal provided at the output pin 6.Accordingly, by increasing or decreasing the duty cycle of the pulsesignal provided at the output pin 6, the output current induced in thesecondary winding 5004 may be increased or decreased to maintain theoutput power at terminal 5864 at an appropriate operational voltage orcurrent level. The output current of the secondary coil 5004 is thensmoothed by capacitors C161 and C201 to provide a DC power output to theoutput terminal 5864.

Terminals 5848, 5860, 5862 and 5864 are preferably provided to aconnector coupling the power supply 5000 to the electronic device to bepowered. In a manner similar to the embodiment discussed above withreference to FIGS. 7A and 7B, the terminal 5860 provides a currentcontrol input and the terminal 5862 provides a voltage control input.Connectors, such as those discussed above with reference to FIGS. 23through 41, may then provide a programming signal to the current controlinput 5860 or the voltage control input 5862. In response to theseinputs, a voltage is applied to a terminal 2 of the integrated circuitU21 to control the duty cycle of the pulse signal output transmitted atoutput pin 6. The current through the secondary coil 5004 is thereforecontrolled to provide an operational voltage or operational current atthe power output pin 5864.

While the embodiment shown at FIG. 1 is configured to receive a DC powerinput, this embodiment could be modified to accept an AC power input by,for example, replacing the input circuit having the inductor L21 with aninput transformer followed by a full bridge rectifier as illustrated inFIGS. 7A and 7B. Also, the aforementioned small form factor designillustrated with reference to FIGS. 7A through 41 may be modified toaccept a DC input by, for example, replacing the input transformer andfull bridge rectifier circuit with a single inductor as shown in theembodiment of FIG. 51.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

The presently disclosed embodiments are therefore to be considered inall respects as illustrative and not restrictive, the scope of theinvention being indicated by the appended claims, rather than theforegoing description, and all changes which come within the meaning andrange of equivalency of the claims are therefore intended to be embracedtherein.

1. A power supply system, comprising: a power source to a provide DCpower; and a control circuit, remote to the power source and in aseparate housing from the power source, to receive the DC power from thepower source and provide a DC power signal to an electronic device,wherein the control circuit includes at least one active component totransmit at least one of a voltage control output or a current controloutput to the power source to control the DC power output from the powersource.
 2. A power supply system, comprising: a power source to aprovide DC power; and a control circuit, remote to the power source andin a separate device from the power source, to receive the DC power fromthe power source and provide a DC power signal to an electronic device,wherein the control circuit includes an amplifier to transmit at leastone of a voltage control output or a current control output to the powersource to control the DC power output from the power source.
 3. A powersupply system, comprising: a power source to provide DC power; a controlcircuit, remote to the power source, to receive the DC power and providea first DC power signal, wherein the control circuit includes at leastone active component to provide at least one of a voltage control outputor a current control output to the power source to control the DC power;and an interface to provide the first DC power signal to a firstelectronic device via a first output port, and a second DC power signalto a second electronic device via a second output port, wherein theinterface includes a voltage regulator to tap off of the first DC powersignal and produce the second DC power signal.
 4. The power supplysystem according to claim 3, wherein the voltage regulator steps up thefirst DC power signal to produce the second DC power signal.
 5. Thepower supply system according to claim 3, wherein the voltage regulatorsteps down the first DC power signal to produce the second DC powersignal.
 6. The power supply system according to claim 3, wherein thevoltage regulator regulates the first DC power signal to produce thesecond DC power signal.
 7. The power supply system according to claim 3,wherein the interface is located within a cable.
 8. The power supplysystem according to claim 3, wherein the interface is located within atip coupled between the power supply and one of the first electronicdevice and the second electronic device.
 9. A power supply system,comprising: a power source to provide DC power; and a control circuit,remote to the power source, to receive the DC power signal from thepower source and provide a DC power signal to an electronic device,wherein the control circuit includes an active component to transmit atleast one of a voltage control output or a current control output to thepower source to control the DC power output from the power source, thecontrol circuit is located in a housing separate from the power source,and the housing is disposed at an end of a cable connecting the powersource and the housing, the voltage control output or the currentcontrol output being transmitted from the control circuit to the powersource via the cable.
 10. A power supply system, comprising: a powersource to provide DC power; a control circuit, remote to the powersource, to receive the DC power signal and provide a DC power signal toan electronic device, wherein the control circuit includes an activecomponent to provide at least one of a voltage control output or acurrent control output to the power source to control the DC power andthe control circuit is located in a housing separate from the powersource and the housing is disposed at an end of a cable coupling thepower source and the housing; and an interface to provide the DC powersignal to the electronic device via a first output port, and to providean additional DC power signal to another electronic device via a secondoutput port, wherein the interface includes a voltage regulator to tapoff the DC power signal and produce the additional DC power signal. 11.The power supply system of claim 10, wherein the interface is locatedwithin a second cable connecting the housing of the control circuit andat least one of the electronic device or the additional electronicdevice.
 12. The power supply system of claim 10, wherein the interfaceis located within a physical enclosure separate from the power sourceand the housing holding the control circuit.
 13. A power supply system,comprising: a power source to provide DC power; and a control circuit,remote to the power source, to receive the DC power from the powersource and provide a DC power signal to an electronic device, whereinthe control circuit includes an amplifier to provide at least one of avoltage control output or a current control output to the power sourceto control the DC power output from the power source, and the controlcircuit is located in a housing separate from the power source, and thehousing is disposed at an end of a cable connecting the power source andthe housing, the voltage control output or the current control outputbeing transmitted from the control circuit to the power source via thecable.
 14. A power supply system, comprising: a power source to provideDC power; a control circuit, remote to the power source, to receive theDC power and provide a DC power signal to an electronic device, whereinthe control circuit includes a amplifier to provide at least one of avoltage control output or a current control output to the power sourceto control the DC power, the control circuit is located in a housingseparate from the power source, and the housing is disposed at an end ofa cable coupling the power source and the housing; and an interface toprovide the DC power signal to the electronic device via a first outputport, and an additional DC power signal to an additional electronicdevice via a second output port, wherein the interface includes avoltage regulator to tap off of the DC power signal and produce theadditional DC power signal.
 15. The power supply system according toclaim 14, wherein the voltage regulator steps up the DC power signal toproduce the additional DC power signal.
 16. The power supply systemaccording to claim 14, wherein the voltage regulator steps down the DCpower signal to produce the additional DC power signal.
 17. The powersupply system according to claim 14, wherein the voltage regulatorregulates the DC power signal to produce the additional DC power signal.18. The power supply system according to claim 14, wherein the interfaceis located within a cable.
 19. A power supply system, comprising: apower adapter to receive input power from an external power source, thepower adapter providing a first DC power signal; and an interface toprovide the first DC power signal to a first electronic device via afirst output port, the interface including a control circuit, thecontrol circuit outputting one of a voltage control output and a currentcontrol output to the power adapter to control the first DC powersignal, the control circuit including at least one active component, andthe interface providing a second DC power signal to a second electronicdevice via a second output port, wherein the interface includes avoltage regulator to tap off of the first DC power signal and producethe second DC power signal.
 20. A power supply system, comprising: apower adapter to receive input power from an external power source, thepower adapter providing a first DC power signal; and an interface tooutput the first DC power signal via a first output port, and output asecond DC power signal via a second output port, wherein the interfaceincludes a voltage regulator to tap off of the first DC power signal andproduce the second DC power signal and also includes a control circuit,the control circuit outputting one of a voltage control output and acurrent control output to the power adapter to control the first DCpower signal, and the control circuit including at least one activecomponent.